Gibson J-185

What're You Doing?
Gary Davis
Posts: 5
Joined: Fri Dec 02, 2022 7:06 pm

Gibson J-185

Post by Gary Davis »

Good morning John and others. This is my first post so forum rules may be a bit disruptive for me for a while.

I am building something resembling the subject guitar. Black walnut B&S and neck with redwood top. This is my third instrument. My first was a baritone ukulele and I just finished an F5 mandolin. Those projects taught me a lot but apparently not quite enough. I have recently been reading this forum and its archives and I have three questions.

1. A post on October 7, 2021 indicates that the Antes plan contains some errors and results in an overbuilt guitar. In particular, I'm confused about the width of the lower back braces. I have the OLF SJ plans and it calls for 1/4" back braces rather than 3/4". Does that sound close for the 185? If so, how does such a significant error find its way into plans without some follow-up or an errata sheet? I have the CADGuitar plans for the 185 as well and it shows 3/4" back braces. What other errors might be lurking in the Antes plan?

2. I understand the 185 is a flattop guitar. The upper bout is flat and the top braces introduce some arch into the lower bout. I've made the neck block with the angled top and bottom per the plans. I'm trying to reconcile how the top remains flat while it is angled toward the soundhole to preserve the fretboard angle. Do the sides on the upper boat follow a similar angle? Help.

3. The Antes plans suggest the back arch is 27'. That seems counter to most of what I see for steel string guitars where the top radius about 28' and the back is 10-12'. What am I missing here?

Thanks to all for taking the time to read my first post and offer advice.

Gary Davis
Billings, Montana
TEETERFAN
Posts: 211
Joined: Fri Sep 07, 2018 12:43 pm
Location: Kansas City, MO

Re: Gibson J-185

Post by TEETERFAN »

Welcome to the forum, Gary. Good to have ya! I am not familiar with Gibsons, but I am sure the other members will be able to help you out. Good luck!
Kevin Doty
Kansas City
MaineGeezer
Posts: 1604
Joined: Wed Aug 13, 2014 12:14 pm

Re: Gibson J-185

Post by MaineGeezer »

Welcome! We're a friendly bunch, and like questions.

I''m afraid I'm no Gibson expert -- or or much of any expert -- but a 3/4" (wide?) back brace sounds rather massive to me. What is its other dimension? The stiffness of a brace comes from its height, not its width, so a brace 1/4" wide by 3/4" high is going to work better than one 3/4" wide by 1/4" high. And it probably won't need to be 3/4" high, so you can make it lighter overall. But I don't know what Gibsons do.

A back radius of 27' does sound odd. I build mine with a 25' top radius and a 15' back radius, which seems to be in the range of what most builders use.
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
tippie53
Posts: 6826
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: Gibson J-185

Post by tippie53 »

Gibsons are different than martins but the back braces are
5/16 wide on front 2
the lower are 3/8 wide and 3/4 high
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Gary Davis
Posts: 5
Joined: Fri Dec 02, 2022 7:06 pm

Re: Gibson J-185

Post by Gary Davis »

Thanks John and others. FYI - I looked at the Antes plans again and it states that the soundboard has a 27' radius not the back. My mistake. I assume if the plans are correct, then the curved back braces will produce the correct radius?

Still I wonder about the neck block and upper bout geometry necessary to achieve the correct neck set. Maybe I'll have time today to go to the shop and look at things a little closer.

Any other wisdom out there?

Gary Davis
tippie53
Posts: 6826
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: Gibson J-185

Post by tippie53 »

not a fan of antes though the radius is within reason . the back should be between 15 and 20 foot
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
tippie53
Posts: 6826
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: Gibson J-185

Post by tippie53 »

I wouldn't radius the entire top that will actuall over stress the top. You want a neck angle that in the end will set you up so you can be in the 1/2 in range of string height at the saddle. This would mean you radius from the top of the sound hole to the neck block.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Stray Feathers
Posts: 540
Joined: Sun Sep 08, 2013 11:39 pm
Location: Ladysmith, BC

Re: Gibson J-185

Post by Stray Feathers »

Re: back braces, some builders use four braces of roughly equal width and depth, and some replace the lower bout braces with lower, wider ones. I don't know how you compare the structural and tonal difference between the two, and I've never seen an explanation, but I would love to know. I've done both, mostly because that's what the particular plan called for. Bruce W.
tippie53
Posts: 6826
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: Gibson J-185

Post by tippie53 »

gibson never used the lower wider ones
Gibson bracing was more crude that martin.
I personally like the wider lower ones so if your not going with tradition use those if you prefer.
The upper 2 are generally between 1/4 in and 5/16 wide and about 1/2 in high often at a 15 ft radius
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Gary Davis
Posts: 5
Joined: Fri Dec 02, 2022 7:06 pm

Re: Gibson J-185

Post by Gary Davis »

John,

In the 2012 thread, you state that the top is "dead flat." How do I reconcile that with your current position that the top bout is radiused between sound hole and neck block? Radiused in section or profile?

I might be better informed after I get back to the shop and look at my sides in the form.

Thanks for your help and clarification.

Gary

BTW - I'm going to go with the thinner lower bout back braces because the 3/4" braces just look too heavy.
Post Reply